Question
If $^\text{n}\text{P}_4= 360,$ find the value of n.

Answer

We have,

$^\text{n}\text{P}_4= 360,$

$\Rightarrow \frac{\text{n!}}{(\text{n}-4)!}=360$]

$\Rightarrow \frac{\text{n}(\text{n}-1)(\text{n}-2)(\text{n}-3)(\text{n}-4)!=360}{(\text{n}-4)!}$

$\Rightarrow \text{n}(\text{n}-1)(\text{n}-2)(\text{n}-3)=6\times 5\times4\times3 $

$\Rightarrow \text{n}=6 \ [13 \text{ by} \text{ comapring}]$

Hence, $\text{n}=6$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free